Here is how I consume audio content at rapid speeds. I've done this for the fast ten years, or so. All thanks goes to the speed feature of iTunes and Audible.
Warning: I'll admit my retention level diminishes greatly using this method.
Step one: Listen to audio at the fastest speed possible for sixty seconds.
Step two: bring the speed down one level at a time until it is understandable and comprehendable.
Try bringing the speed back up if you feel you have adjusted or just want to try a faster speed again.
Sometimes it depends on the speaker, audio quality, and hardware.
Extra tip: Youtube has this feature too. Great for lecture type content.